Optimizing dispersal corridors for the Cape Proteaceae using network flow

We introduce a new way of measuring and optimizing connectivity in conservation landscapes through time, accounting for both the biological needs of multiple species and the social and financial constraint of minimizing land area requiring additional protection. Our method is based on the concept of network flow; we demonstrate its use by optimizing protected areas in the Western Cape of South Africa to facilitate autogenic species shifts in geographic range under climate change for a family of endemic plants, the Cape Proteaceae. In 2005, P. Williams and colleagues introduced a novel framework for this protected area design task. To ensure population viability, they assumed each species should have a range size of at least 100 km2 of predicted suitable conditions contained in protected areas at all times between 2000 and 2050. The goal was to design multiple dispersal corridors for each species, connecting suitable conditions between time periods, subject to each species' limited dispersal ability, and minimizing the total area requiring additional protection. We show that both minimum range size and limited dispersal abilities can be naturally modeled using the concept of network flow. This allows us to apply well-established tools from operations research and computer science for solving network flow problems. Using the same data and this novel modeling approach, we reduce the area requiring additional protection by a third compared to previous methods, from 4593 km2 to 3062 km , while still achieving the same conservation planning goals. We prove that this is the best solution mathematically possible: the given planning goals cannot be achieved with a smaller area, given our modeling assumptions and data. Our method allows for flexibility and refinement of the underlying climate-change, species-habitat-suitability, and dispersal models. In particular, we propose an alternate formalization of a minimum range size moving through time and use network flow to achieve the revised goals, again with the smallest possible newly protected area (2850 km2). We show how to relate total dispersal distance to probability of successful dispersal, and compute a trade-off curve between this quantity and the total amount of extra land that must be protected.     

Costs of expanding the network of protected areas as a response to climate change in the Cape Floristic Region

The expansion of protected areas is a critical component of strategies to promote the continued existence of biodiversity (i.e., life at all levels of biological organization) as climate changes, but scientific, social, and economic uncertainties associated with climate change are some of the major obstacles preventing such expansion. New models of climate change and species distribution and new methods of conservation planning now make it possible to explore the uncertainties associated with climate changes and species responses. Yet few reliable estimates of the costs of expanding protected areas and methods for determining these costs exist, largely because of the many (and uncertain) determinants of these costs. We developed a cost-accounting model to estimate the range in costs of various options for expanding protected areas and to explore the variables that drive these costs. Model development was informed by an existing plan to expand protected areas in the Cape Floristic Region of South Africa to address species conservation under a scenario of climate change. The 50-year present value of total costs varied from US$260 million ($1077/ha) for an off-reserve option that involves agreements with landowners and no compensation of forgone production and associated revenue to $1020 million ($4228/ha) for an on-reserve option that involves land acquisition and protection. The costs of acquiring land or compensating landowners for forgone production and development opportunities were the major drivers of the total costs across all options because most of the area identified in the protected-area expansion plan consisted of urban and high-quality agricultural lands. Total costs were also affected by changes in protected area extent and discount rate. Model-generated outputs such as these may be useful for informing implementation strategies and the allocation of future efforts in monitoring, data collection, and model development.     

Growth, phenology and reproduction of an arid-environment winter ephemeral Dimorphotheca pluvialis in response to combined increases in CO2 and UV-B radiation

The winter ephemeral Dimorphotheca pluvialis was grown in open-top chambers in ambient or elevated CO2 (350 or 650 micromol mol(-1)), combined with ambient (2.39 to 7.59 kJ m(-2) d(-1)) or increased (4.94 to 11.13 kJ m(-2) d(-1)) UV-B radiation. Net CO2 assimilation rate and leaf water use efficiency increased in elevated CO2, but increased UV-B did not affect gas exchange. Leaf biomass was greater under increased UV-B, but vegetative biomass was unaffected in elevated CO2. Initiation of reproduction was delayed, and proportional investment in reproductive biomass at harvest was reduced in elevated CO2. Increased UV-B stimulated reproduction, particularly in ambient CO2, but also in elevated CO2 at a later stage. Changes in reproductive phenology and prolonged development in elevated CO2 during the stressful late season could indirectly be detrimental to reproductive success of D. pluvialis, but stimulation of reproduction by enhanced UV-B may to some extent mitigate this.     

Occupational fatality under-reporting in rural areas of the Western Cape Province, South Africa

Following a previously published study which reported that 28% of occupational fatalities in the Cape Town metropole of the Western Cape Province of South Africa had not been reported in terms of statutory regulations, this rural-based study found that 85% of occupational fatalities were unreported. Two hundred and twenty four work-related deaths occurring in 10 rural magisterial districts in the Western Cape Province over a two and a half year period (January 1990-August 1992) were identified by examination of state mortuary death registers and police inquest reports. A review of the registers of the occupational safety inspectorate found that only 15% (n = 33) of these deaths had been reported. Drowning (68%), chemical poisoning (10%) and tractor accidents (9%) accounted for the greatest number of unreported fatalities. Only 5% of fatalities in women were reported. Underreporting of even the most direct occupational accidents highlights the gross inadequacy of the current reporting system for rural areas. Greater co-ordinated efforts within and between the government departments of health and labour are urgently required to address environmental hazards in rural areas and in particular on farms. Differential underreporting of occupational fatalities by gender to the disadvantage of women needs further investigation.     

Potential responses of terrestrial biodiversity in Southern Africa to anthropogenic climate change

Key studies supported by species-level data collection have provided early indications of the potential implications of unmitigated change for the ecosystems and biodiversity of southern Africa. These suggest a significant threat to biodiversity, both from changing bioclimatic suitability and changing atmospheric CO₂ level that seems to affect the competitive balance between woody and herbaceous plants in the dominant savanna biome of this region. Modeling efforts suggest significant implications of unmitigated climate change for this region, but assumptions underpinning methods such as bioclimatic modeling must be recognized, some of which might lead to over estimates of the rate and extent of the potential impacts. General trends and level of coincidence between various types of studies do support a high degree of concern for a substantial portion of southern African biodiversity under unmitigated climate-change scenarios. The most significant changes in ecosystem structure (both increases and decreases in woody plant cover), and associated faunal diversity changes, are projected in the dominant savanna vegetation type in this region, while the most significant biodiversity loss is projected for the winter rainfall region. Follow-up work to detect early signs of climate change identify regions of high- and low-potential impacts, and experimental work to test some important hypotheses relating to the future evolution of climate-change impacts across the region are very few and urgently required.     

Typologies of collaborative governance for scaling nature-based solutions in two strategic South African river systems

Scaled up planning and implementation of nature-based solutions requires better understanding of broad characteristics (typologies) of the current governance and financing landscape, collaborative approaches amidst local complexities, and factors of scalability. An inventory was compiled of water-related ecological infrastructure intervention projects in two river systems in South Africa, incorporating actor, environmental, social, and financial dimensions and benefits. Qualitative participatory analysis revealed eight typologies. Post-hoc classification analysis determined similarities and/or unique characteristics of seven quantitative typologies. Key characterising factors included the complexity/size of financial flows, complexity of partnership/governance arrangements, mandates/goals of actors, type of ecological infrastructure, trade-offs in investment in ecological/built infrastructure, and the model used for social benefits. Identified scalable typologies offer structures suited to increased investment, with other typologies offering specialised local value. A range of ecological infrastructure intervention typologies with differing biophysical and socioeconomic outcomes provide choices for investors with specific goals, and benefits to landscape actors.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01531-z.